In an attempt to evaluate the efficacy, optimal dose, route of administration, and toxicity of various anti-leukemic and anti-neoplastic agents, the members of the Children's Cancer Study Group A treat children with hematopoietic and solid malignancies within the confines of mutally agreed upon protocols. In addition, certain adjuvant therapy is studied such as plasma, blood products, treatment of central nervous system infiltration and other local disease treatment. Ancillary information such as survival time, incidence of complications and incidence of prolonged survival is gathered and evaluated. Certain investigational drugs are tested to determine adequate dosage, optimal dose administration regimens, efficacy and toxicity.